概要：
[if !supportLists]1. [endif]执行流程解析
[if !supportLists]2. [endif]myBatis插件开发
一、执行流程解析
配置文件解析configuration：
讲解解析流程之前先回顾一下myBatis 中配置文件的结构：
mybatis-config.xml
<configuration>
<properties/>
<settting/>
<typeHandlers/>
<..../>
<mappers/>
</configuration>
mybatis-mapper.xml
<mapper >
<cache/>
<resultMap/>
<select/>
<update/>
<delete/>
<insert/>
</mapper>
配置文件的解析流程即是将上述XML描述元素转换成对应的JAVA对像过程，其最终转换对像及其关系如下图：
配置元素解析构建器
>org.apache.ibatis.builder.xml.XMLConfigBuilder
>org.apache.ibatis.builder.xml.XMLMapperBuilder
>org.apache.ibatis.builder.xml.XMLStatementBuilder
>org.apache.ibatis.builder.SqlSourceBuilder
>org.apache.ibatis.scripting.xmltags.XMLScriptBuilder
>org.apache.ibatis.builder.annotation.MapperAnnotationBuilder
sql statement 构建流程源码：
>org.apache.ibatis.session.SqlSessionFactoryBuilder#build()
//1.Config.xml 文件解析
>org.apache.ibatis.builder.xml.XMLConfigBuilder#parse()
>org.apache.ibatis.builder.xml.XMLConfigBuilder#parseConfiguration()
>org.apache.ibatis.builder.xml.XMLConfigBuilder#mapperElement()
// 2.Mapper.xml 文件解析
>org.apache.ibatis.builder.xml.XMLMapperBuilder#parse()
>org.apache.ibatis.builder.xml.XMLMapperBuilder#configurationElement()
>org.apache.ibatis.builder.xml.XMLMapperBuilder#buildStatementFromContext()
//3.Statemen sql块解析
>org.apache.ibatis.builder.xml.XMLStatementBuilder#parseStatementNode
>org.apache.ibatis.builder.MapperBuilderAssistant#addMappedStatement()
// 4.动态SQL脚本解析
>org.apache.ibatis.scripting.xmltags.XMLLanguageDriver#createSqlSource()
>org.apache.ibatis.scripting.xmltags.XMLScriptBuilder#parseScriptNode()
>org.apache.ibatis.scripting.xmltags.XMLScriptBuilder#parseDynamicTags()
会话创建SqlSession
首先我们还是先来了解一下会话对像的组成结构如下图：
会话构建源码解析:
>org.apache.ibatis.session.defaults.DefaultSqlSessionFactory#openSession(boolean)
>org.apache.ibatis.session.defaults.DefaultSqlSessionFactory#openSessionFromDataSource
>org.apache.ibatis.transaction.jdbc.JdbcTransactionFactory#newTransaction()
>org.apache.ibatis.session.Configuration#newExecutor()
>org.apache.ibatis.executor.SimpleExecutor#SimpleExecutor
>org.apache.ibatis.executor.CachingExecutor#CachingExecutor
//执行器插件包装
>org.apache.ibatis.plugin.InterceptorChain#pluginAll(executor)
>org.apache.ibatis.session.defaults.DefaultSqlSession#DefaultSqlSession()
方法执行StatementHandler
StatementHandler 源码解析
>org.apache.ibatis.session.defaults.DefaultSqlSession#selectList()
>org.apache.ibatis.executor.CachingExecutor#query()
>org.apache.ibatis.executor.BaseExecutor#query()
>org.apache.ibatis.executor.BaseExecutor#queryFromDatabase
>org.apache.ibatis.session.Configuration#newStatementHandler
org.apache.ibatis.executor.statement.BaseStatementHandler#BaseStatementHandler
org.apache.ibatis.session.Configuration#newParameterHandler
org.apache.ibatis.plugin.InterceptorChain#pluginAll(parameterHandler)
org.apache.ibatis.session.Configuration#newResultSetHandler
org.apache.ibatis.plugin.InterceptorChain#pluginAll(resultSetHandler)
>org.apache.ibatis.plugin.InterceptorChain#pluginAll(statementHandler)
>org.apache.ibatis.executor.BaseExecutor#getConnection
>org.apache.ibatis.executor.statement.PreparedStatementHandler#instantiateStatement
>org.apache.ibatis.executor.statement.PreparedStatementHandler#parameterize
>org.apache.ibatis.scripting.defaults.DefaultParameterHandler#setParameters
org.apache.ibatis.type.BaseTypeHandler#setParameter
org.apache.ibatis.type.UnknownTypeHandler#setNonNullParameter
org.apache.ibatis.type.IntegerTypeHandler#setNonNullParameter
Mapper接口实例构建
二、myBatis插件开发
插件的四大扩展点
[if !supportLists]1. [endif]Executor
[if !supportLists]2. [endif]StatementHandler
[if !supportLists]3. [endif]ParameterHandler
[if !supportLists]4. [endif]ResultSetHandler
分页插件实现：
用户在接口中声明Page 对像实现后，由插件实现自动分页。使用示例如下：
public class Page implements java.io.Serializable {
private int szie; // 每页大
private int number; // 当前页码
}
page参数声明
@Select("select * from user")
List<User> selectByPage(String name, Page page);
客户端调用
mapper.selectByPage("小明", new Page(3, 2))
select * from user limit 10,20
实现目标分解：
[if !supportLists]1. [endif]修改修改SQL 并添加 limit 语句
[if !supportLists]2. [endif]判断方法参数中是否有Page对象
[if !supportLists]3. [endif]取出Page对象 生成limit 语句
[if !supportLists]4. [endif]上述操作必须在PreparedStatement 对像生成前完成
